Abstract

River confluence is an important element of river system. The entrance flow from the river branch into the main river causes extensive variation in flow pattern and creation of vortex. Because of these, a scour hole is developed just downstream of the river confluence. These phenomena can accelerate the rate of bank erosion, bring problems for navigation and may causes failure of the bridge or structures nearby. In this paper the geometric dimensions of scour hole have been studied. To reach such goal, first by using the dimensional analysis, general non-dimensional equations were developed. Then the experimental tests were conducted for three different confluence angles 60, 75 and 90 degree, under different hydraulic conditions. Finally, relationship were developed for prediction of scour hole depth.

Keywords: river confluence, scour, lateral channel, confluence angle